Mobile computing devices, such as mobile or wireless stations, cell phones, radios, laptops, wireless communication devices and the like, operate with a power storage device with a limited energy supply, such as a battery, fuel cell or the like. A mobile computing device needs a power source and, in many cases, this power source is a battery. For instance, cellular phones use various types of batteries to operate. The amount of time a mobile station can typically operate before the energy of the battery is consumed (which is often referred to as “battery life”), is often an important criteria that consumers use in choosing one brand or type of mobile computing device over another brand. The terms battery, energy storage device and power storage device are used interchangeably herein.
While the power storage device is generally rechargeable, it may not be convenient or even possible for a user to recharge. Accordingly, there is a need to maximize the useful operational time of a wireless computing device. Additionally, different operating environments can cause the user to be surprised and/or frustrated when the battery runs out much more quickly than would typically be expected by the user. Thus, a variation from the norm or unexpected short battery life is very undesirable from a user perspective.
This is a particularly relevant problem for mobile computing devices running applications supported by an applications server because of the power drain due to the wireless data exchange between the mobile device and the server, since each upload or download causes the consumption of energy in the mobile device and server. The problem is especially acute in the mobile device, which is typically battery powered and has finite energy available. Accordingly, it is desirable to improve battery life of mobile devices operating on any network. For example, in connection with the operation of a 3G network, a mobile device is typically in a persistent internet communication with an application server. It is also desirable to reduce the inefficiencies on the 3G network.
In devices running applications in communication with an application server, a persistent internet protocol (IP) session is typically used, in accordance with HTTP1.1, such that the IP session remains open for a predefined period, such as 30 minutes. The use of persistent IP sessions is helpful in that each opening and closing of an IP session requires the transmission of overhead data. Thus it is beneficial to maintain a persistent IP session, from the standpoint of minimizing the amount of data traffic and consequently minimizing the energy consumption in the mobile device.
Operation over a wireless network involves operating according to a wireless protocol, such as the Universal Mobile Telecommunications Standard (UMTS) or another protocol. Wireless protocols such as UMTS provide different transceiver operating states, according to needs to transfer different amounts of data. Transceiver operating states with faster data transfer capabilities for transferring higher amounts of data typically require higher power from the device energy source of the device. Accordingly, if the amount of data to be transmitted is large, the wireless transceiver operates in an active, or high data rate and high power state, and conversely if the amount of data to transmit is small the transceiver operates in an idle, or low data rate and low power, state.
During persistent IP sessions there may be periods when there is no data traffic. During these periods of no data traffic it is often beneficial from the standpoint of energy consumption for the wireless transceiver in the mobile device to transition to an idle state. In a UMTS network, during periods of no data transfer, the amount of time that the transceiver stays in an active state prior to transitioning to idle depends on a network determined inactivity timer. Network inactivity timers vary greatly from network to network. In some networks the inactivity timer approximates the maximum round trip time (RTT), which is the maximum amount of time for a mobile device to send a message to a recipient, such as an application server, and for the recipient to receive the message and send an acknowledgement message, and for the mobile device to receive the acknowledgement message. The network inactivity time is typically set to a worst case RTT value. A worst case RTT value may occur under adverse signaling conditions such as low signal power, low receiver level, high interference or poor received data quality. Under normal signaling conditions the worst case RTT value results in the mobile transceiver staying in the active state for longer than is necessary.
Thus it would be beneficial and there is a need for a mobile device to measure the actual RTT, and to request the transition to idle based on the measured RTT, before the expiration of the network defined inactivity timer.
In other networks, the network inactivity timer is often set to a longer value, which may include an amount of time for a subsequent message to be sent by the mobile device to the recipient, or by the recipient to the mobile device. For example in web-browsing applications there is a high probability of a subsequent message occurring within a time, T, which is typically longer than RTT. Thus there is a wide range of network inactivity periods, depending on network settings.
In more detail, a mobile device operating on a first network may transition to idle after a short period determined primarily by the network configuration, such as 3 seconds, and the mobile operating on a second network may transition to idle after a much longer period determined by the expected time of a subsequent message, such as 90 seconds. The value of T may be determined by a worst case application running on the mobile device, such as a browser application, where there is a high probability of a subsequent message. For example, for a web-browsing application it may be determined that there is a high probability of a delayed mobile device user response. Conversely many applications have virtually immediate subsequent responses.
Thus it would be beneficial for a mobile device to request a transition to idle before the expiration of the network defined inactivity timer, such that the request occurs after a predefined period which depends on the running applications. For example, if the running application only includes applications with a low probability of subsequent data transfer, such as a data pushing service from an application server, then transition to idle may occur after a period depending on the RTT. If the running application includes an application with a high probability of subsequent data transfer, such as a web browser, then the transition to idle may occur after a period depending on T, which is typically much longer. Alternatively if the running application includes an application with a high probability of subsequent data transfer, such as a web browser, then the transition to idle may occur based on the expiration of the default network defined inactivity timer.
It would be considered an improvement in the art, if the energy drain in a wireless communication device could be minimized thereby extending battery life, and network efficiencies could be enhanced.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve the understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention. It will further be appreciated that certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. It will also be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study except where specific meanings have otherwise been set forth herein.